Tooth size discrepancies among different malocclusions in a Japanese orthodontic population.
OBJECTIVE
To identify the possible sex differences in anterior and overall tooth size ratios and to evaluate whether any differences exist in tooth size ratios and distributions of subjects with clinically significant tooth size discrepancies among Angle Class I, Class II, and Class III malocclusion groups with the corresponding skeletal characteristics in a Japanese population.


METHODS
Each malocclusion group comprised 60 subjects (30 males and 30 females). The mesiodistal width from first molar to first molar was measured on each pretreatment cast to the nearest 0.01 mm using digital calipers, and the anterior and overall ratios were calculated. Student's t-test, Welch t-test, analysis of variance, and chi2-test were performed for statistical analysis.


RESULTS
No statistically significant sex differences were found in anterior or overall ratio in any group. No significant differences in anterior or overall ratios were found among the malocclusion groups. No significant differences were found between the distributions of subjects with clinically significant tooth size discrepancies, categorized by the Bolton standard deviation definition and by the actual amount of change calculated for tooth size correction in millimeters, among the malocclusion groups except for the mandibular correction for the overall ratio between Class I and Class III subjects.


CONCLUSIONS
Bolton's values can be used with confidence for the typical Japanese orthodontic population. The use of the actual millimeters of correction for the tooth size ratios could help orthodontists avoid underestimating the prevalence of clinically significant tooth size discrepancies.
Endo
Toshiya
T
Orthodontic Dentistry, The Nippon Dental University Niigata Hospital, Niigata, Japan. endoto@ngt.ndu.ac.jp
Abe
Ryota
R
Kuroki
Hiroo
H
Oka
Kenji
K
Shimooka
Shohachi
S
D044466:Asian People; D001641:Bicuspid / Q000473:pathology; D003481:Cuspid / Q000473:pathology; D005260:Female; D006801:Humans; D007180:Incisor / Q000473:pathology; D007564:Japan; D008297:Male; D008310:Malocclusion / Q000473:pathology*; D008311:Malocclusion, Angle Class I / Q000473:pathology; D008312:Malocclusion, Angle Class II / Q000473:pathology; D008313:Malocclusion, Angle Class III / Q000473:pathology; D008963:Molar / Q000473:pathology; D009811:Odontometry; D012189:Retrospective Studies; D012727:Sex Characteristics; D014070:Tooth / Q000473:pathology*